Effects of chronotherapy on blood pressure control in non-dipper patients with refractory hypertension.

BACKGROUND Refractory arterial hypertension (RAH) is frequently associated to a non-dipping blood pressure (BP) pattern; this profile has been shown to have a worse clinical prognosis. It is a common clinical practice that patients receive anti-hypertensive medication preferentially in the morning. Non-dipping could be related to the timing of anti-hypertensive drug administration. We analysed whether switching anti-hypertensive medication to bedtime could improve BP control in non-dipper patients with RAH. METHODS Twenty-seven consecutive patients with RAH and non-dipper or riser BP pattern on ambulatory blood pressure (ABP) monitoring were studied before and after 6 weeks of a change in the timing of anti-hypertensive medications. The intervention consisted of shifting all non-diuretic anti-hypertensive drugs from morning to evening, maintaining the same drugs at the same doses. A parallel group of 12 consecutive patients with similar characteristics and no changes in the therapeutic regimen formed the control group. RESULTS There were 59% women, mean age 65.7 ± 8.4 years. They were treated with 4 ± 0.7 anti-hypertensive drugs, 90% administered in the morning. At baseline, diurnal and nocturnal ABP averaged 141.6 ± 10.6/81.5 ± 9.3 and 141.7 ± 11/78 ± 8.8, respectively. After the drug shift, mean diurnal and nocturnal ABP was 140.5 ± 10.4/80.5 ± 9.6 and 135.7 ± 12.5/73.8 ± 9.3 (P = 0.005 and 0.04 for systolic and diastolic ABP), 15% of the patients restored a normal ABP circadian rhythm. No changes were observed in the control group. CONCLUSION In non-dipper or riser patients with RAH, changing the timing of anti-hypertensive medication to the evening could improve BP control.